1. Field of the Invention
This invention relates generally to surgical instruments having an elongate configuration with an operative section at a distal end and an operating section at a proximal end, and more specifically to such instruments which include a ratchet assembly in the operating section.
2. Discussion of the Prior Art
Many surgical instruments have a narrow, elongate shaft or tube which extends between a proximal end and a distal end. An operative section including for example the jaws of a clamp, have been disposed at the distal end and operated through the tube by an operating section, such as scissors handles, at the proximal end. These instruments are often characterized by other operative sections including clips, clamps, cutters, spreaders and other structures which perform an operative function for the instrument. The surgical instruments can also differ in the nature of the operative section at the proximal end, which is typically configured to be engaged by the surgeon to be moved to create the desired operative effect at the distal end of the instrument. The elongate tube or shaft which separate the operative section from the operating section enables the surgeon reach deeply into a body cavity through a relatively small incision.
One such instrument of the past includes an operative section in the form of a clamp having two jaws moveable relative to each other by operation of the operating section. This operating section has a pair of scissorshandles which are relatively moveable in a natural plane of operation and which carry a pair of opposing flanges each having a series of grooves. The grooves are engagable to the lock the jaws of the operative section at some predetermined relationship between a closed configuration and a open configuration. The series of grooves extend transverse to the relative movement of the handles and have peaks and valleys which extend laterally of the natural plane of movement. As a consequence, the two series of grooves can only be engaged and disengaged by bending the first and second handles in opposite lateral directions. This bending typically requires two hands or substantial strength in one hand of the user.
In the past, the two series of grooves are exposed and therefore easily contaminated with debris which can interfere with their operation. Accordingly, the surgeon has been left with a need for an elongate surgical instrument having a ratchet in its operating section which is operable with a minimum of force using a natural scissors movement, and which provides for a clean and effective operation of the instrument.
In accordance with the present invention, these deficiencies of the prior art have now been overcome with an operating section including a ratchet assembly carried by a first scissors handle having a first finger support and a second scissors handle having a second finger support. The ratchet assembly can be characterized by a ratchet pawl having a fixed relationship with the second scissors handle, and a series of ratchet teeth having a fixed relationship with an outer portion of the first finger support and pivotal relationship with an inner portion of the first finger support. In the normal operation of the scissorshandles, pressure is directed against the inner portion of the first finger support to close the scissorshandles and progressively engage the series of ratchet teeth with the ratchet pawl. This engagement of the ratchet assembly is achieved without any lateral movement of the scissors handles and totally within the normal plane of operation. In order to open the scissorshandles, normal operation exerts a pressure against the outer portion of the first scissors handle which causes the series of ratchet teeth to pivot on the first scissors handle and away from the ratchet pawl on second scissors handle. This disengagement of the ratchet assembly is achieved without any lateral movement of the scissors handles and totally within the normal plane of operation. By disengaging the ratchet assembly, the scissors handles can be further separated to open, or otherwise operate, the operative device at the distal end of the instrument.
In one aspect of the invention, the instrument is characterized by an elongate body having an axis extending between a proximal end and a distal end. An operative section is disposed at the distal end of the elongate body and a handle assembly is disposed at the proximal end of the elongate body. The handle assembly is moveable relative to the proximal end of the elongate body to operate the operative section between a first configuration and a second configuration. The handle assembly includes a first scissors handle and a second scissors handle that is moveable relative to the first scissors handle between a closed position wherein the first scissors handle has a proximate relationship with the second scissors handle and the operative device is in the first configuration, and an open position wherein the first scissors handle has a spaced relationship with the second scissors handle and the operative device is in the second configuration. A ratchet assembly is coupled to the handle assembly for progressively locking the first scissors handle relative to the second scissors handle at a predetermined position to maintain the operative device in a predetermined configuration. The ratchet assembly includes a series of ratchet teeth and a ratchet pawl which is moveable relative to the teeth to engage at least one of the teeth at the predetermined position. A finger support included in one of the first scissors handle and the second scissors handle has an outer portion that is moveable relative to the one of the first scissors handle and the second scissors handle to disengage the ratchet pawl from the series of ratchet teeth and facilitate movement of the first scissors handle toward the spaced relationship with the second scissors handle. This movement permits further operation of the operative device toward the second configuration.
In a further aspect of the invention, a method of operation is disclosed for actuating an operative device on a distal end of a surgical instrument. The method includes the steps of providing the instrument with a handle assembly including a first scissors handle, a second scissors handle and a ratchet assembly. The ratchet assembly is formed with a series of ratchet teeth and a ratchet pawl. A finger support is formed on the first scissors handle in a moveable relationship with the first scissors handle. Closing the first scissors handle relative to the second scissors handle progressively engages the series of ratchet teeth with the ratchet pawl. By moving the first finger support to disengage the ratchet pawl from the series of ratchet teeth, the first scissors handle can be opened relative to the second scissors handle.